1. Field of the Invention
The present disclosure relates to a spray gun and, more specifically, a spray with an ergonomic design that still allows automatic shut off when a handle is released, even accidentally.
2. Background of the Art
Such spray guns are customarily operated by a liquid medium under high pressure. Work with spray guns is characterized by high physical stress for the operator as a result of the high holding and recoil forces. In addition, a high risk potential is created by the rebounding of material and the high energy content of the liquid jet, such as a water jet. On the one hand, this requires a construction with a good ergonomic design and the highest safety standard and, on the other hand, that only correspondingly instructed personnel trained for the work with high-pressure water jets are permitted to work with spray guns. Additionally, if spray guns are accidentally dropped, the high pressure spray must be automatically turned off to prevent the spray gun (and any associated tubing) from whipping about and causing injury and damage.
Mechanical lever systems generally require the application of an operating or holding force by the operator In this case, the operator's hand must necessarily always remain in contact with the lever. During a fairly long switch-on period, this leads to fatigue or even to cramps in the switching hands. As a result, safety-critical situations may arise; for example, because of the fact that the switch-off cannot take place or can only take place in a delayed manner. It is known from practice that, because of the strained working position, the operating personnel frequently fixes the lever devices by simple means, such as wooden wedges, wire or adhesive tape, against safety regulations, in order to reduce the holding force.
Complex systems of electronic off-on controls are known using contactless electronic proximity sensors. The sensor converts a physical quantity to an electric signal and utilizes its change for generating a switching function. Here, the influencing element, which the operator utilizes for the switching, is of a passive nature in that no communication takes place between the operating element and the proximity sensor. This results in the disadvantage of this state of the art that the system can easily be disturbed or even unintentionally switched as a result of outside influences, such as magnetic or electric fields, vibrations or temperatures. The device is also relatively expensive, and electronic failure might be catastrophic.
U.S. Pat. No. 7,083,124 (Bednorz et al.) describes an ergonomic handle for a spray gun that has contactless actuation of the spray gun without moving parts takes place by an active system which is distinguished by the fact that the actuating element, preferably a transponder, communicates with a reading station of an electronic evaluating device within the spray gun. The transponder is a microelectronic circuit with a transmitting and receiving antenna, a control logic and a fixedly stored safety code as well as an energy accumulator which provides the energy for the return of the safety code. The transponder receives energy packets pulsed at regular intervals from the reading unit of the spray gun and returns information. This takes place by way of antennas in the handle tube which are arranged in pairs in order to generate a concentric field without pole points so that a uniform defined switching interval is ensured.
U.S. Pat. No. 5,740,968 (Mueller) describes a high pressure industrial washdown gun. The gun comprises a body having a hand grip portion, a trigger, a flow control valving system and a conduit for directing the water to the interior of the gun body. The valving system includes a containment sleeve, a connector, a nozzle assembly, a valving rod, and a central water flow passage extending therethrough. A tapered seat surrounds the flow passage. The valving rod includes a nose portion, an enlarged diameter head, and an elongated stem. The valving rod slides within a guide which positions it relative to the containment sleeve. A return spring is provided for the valving rod. A locking mechanism is provided for the handle.
High pressure systems with which the handle may be associated are well known in the art such as those disclosed in U.S. Pat. Nos. 7,083,120; 7,028,925; 6,460,787; 6,273,345; and the like.
Alternative systems are still necessary, especially if those systems can meet the functional, ergonomic and safety needs of the industry.